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Sumberdaya genetik dalam ekosistem. I. PERUBAHAN GENETIK DI ALAM DAN PRODUKSI DIVERSITAS GENETIK. Adaptation. Genetic change. Genetic Diversity. Change of environmental conditions. organism. Natural selection. Variation. 1. Adaptation. Adaptation is :

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Sumberdaya genetik dalam ekosistem

Sumberdayagenetikdalamekosistem


I perubahan genetik di alam dan produksi diversitas genetik
I. PERUBAHAN GENETIK DI ALAM DAN PRODUKSI DIVERSITAS GENETIK

Adaptation

Genetic change

Genetic Diversity

Change of environmental conditions

organism

Natural selection

Variation


1 adaptation
1. Adaptation GENETIK

Adaptation is :

any aspect of an organism or its parts that is of value in allowing the organism to withstand conditions of the environment


Why the organisms have to adapt
Why the organisms have to adapt? GENETIK

  • Enable an organism to better use resources

  • Provide protection from environmental stresses and pressures

  • Modify local environments to the benefit of the organism

  • Facilitate reproduction


TO GENETIKSURVIVE

ADAPTATION?


2 natural selection
2. Natural selection GENETIK

  • Review: overpopulation, unequal survival, unequal reproduction, microevolution

  • Only factor that generally adapts a population to its environment

  • The other three factors may effect populations in positive, negative, or neutral ways


Fig GENETIK1 . The illustration of natural selection


  • Examples: GENETIK

    • Herbivores higher for white flowered plants than red flowered – red-flowered alleles (R) increase

    • Pollinators attracted by white flowers rather than red flowers – white flower alleles (r) increase.

  • Natural selection accumulates and maintains favorable genotypes


Types of natural selection
Types of natural selection GENETIK

1. Directional

2. Stabilizing

3. Diversifying

4. Sexual


1 directional

Type of natural selection GENETIK

1. Directional

  • Phenotype moves toward one end of the range

  • Ex. Beak size in Galapago ground finch

    • During dry years big beaks advantageous and increase in frequency.

Fig. 23.13


2 stabilizing selection
2. Stabilizing selection GENETIK

Fig. 23.12 Frequency of individuals showing a range of phenotypes


3 diversifying
3. Diversifying GENETIK

  • Selects for two ends of a range

  • Can result in balanced polymorphism

  • Ex. Beak type in black-bellied seedcrackers

    • Two types of seeds – hard and soft

    • Intermediate billed birds inefficient at feeding on either type

Fig. 23.14



3 variation
3. Variation GENETIK

Genotype level

The natural variability

Phenotype level


Cause of variation
Cause of Variation GENETIK

  • Mutation is a permanent change in the DNA sequence that makes up a gene. Mutations range in size from a single DNA building block (DNA base) to a large segment of a chromosome


electromagnetic radiation ( GENETIK x-rays and gamma rays)cause breaks in phosphodiester bonds and result chromosome mutations like inversions, translocation, duplications and deficiencies


Mutation in a GENETIKmicroRNA converts petals to stamens. The mutants of petunia and snapdragon show marked similarity. The studies revealed that, due to a common gene defect, the 'plan' underlying the control of floral organ identity is impaired - resulting in 'the wrong organ at the wrong place'.Image: MPI for Plant Breeding Research


Fig 2. The Hardy-Weinberg equilibrium of allele frequencies in non-evolving populations

This equilibrium will hold true no matter what the frequencies of the alleles in the parent population. Try it with p = .24 and q = .76, for example, in a population of 1000 peas.


Types of variation a phenotypic variation
Types GENETIKof variationa. Phenotypic Variation

  • Combination of heritable and non-heritable traits

  • Phenotype is the

    cumulative product of:

    • Inherited genotype

    • Environmental influences

  • Only the genetic component

    can be selected

Fig. 23.7 Same genes, different seasons


B genotypic variation
b. Genotypic variation GENETIK

  • Expressed in these ways:

    • Quantitative (continuous – multilocus?)

      • ex. plant height

    • Discrete (single locus?)

      • ex. flower color

  • Measured by:

    • Gene diversity - % heterozygosity

      • Human – 14%

    • DNA base diversity

      • Human – 0.1 %


C geographic variation
c. Geographic variation GENETIK

  • Between or within populations

  • Natural selection working in response to differences in environment

  • Genetic drift

  • Cline = graded

  • geographic change

Fig. 23.8 Geographical distribution of

variation in Yarrow plants


Ii seleksi dan domestikasi
II. SELEKSI DAN DOMESTIKASI GENETIK

Ddi

Directed selection

  • Human:

  • construct and manipulate the environment

  • Determine and select for traits

  • Cultivate & propagate

Agricultural species

(live, grow &reproduce)

DOMESTICATION


Methods of directed selection
Methods of Directed Selection GENETIK

  • Mass Selection

  • Pure Line Selection

  • Production of Synthetic varieties

  • Hybridization

  • Induced Polyploidy

  • Biotechnology


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